This invention relates generally to a planting apparatus, and more particularly to a planting apparatus wherein the preselected linear seed or plant spacing in the growing medium (hereinafter the "field") is adjustable while the planting apparatus is in motion, and is accurately determined and delivered to the field irrespective of any wheel slippage or sliding by the planting apparatus that ordinarily occurs in planting operations.
Farming is a highly labor intensive and cost driven activity, and the farming industry is constantly striving to decrease farm labor, decrease related farm costs, and increase farm yields (often measured on a yield per area, such as on a yield per acre basis). As a consequence, present day farming techniques employ, among other things, the automated planting or transplanting (collectively "planting") of crops.
Present day automated planting is ordinarily accomplished by having a moving vehicle (hereinafter "tractor") pull a planting apparatus having one or more seed or plant dispensing devices (collectively "seed dispensers") across a field. The seed dispensers are often arranged in one or more rows on the frame of the planting apparatus, and the rows on the frame are oriented transversely to the direction of travel by the tractor. The seed dispensers are ordinarily arranged at distances corresponding to the width of furrows in the portion field to be planted by the planting apparatus.
The rate at which seeds or plants (collectively "seeds") are dispensed by the seed dispensers is generally determined by a drive mechanism which operates a seed metering apparatus, such as a rotating seed dispensing disc, which has a discrete number of holes or pockets ("holes") which in turn dispense a discrete number of seeds per revolution of the drive mechanism or seed metering device. The drive mechanism, in turn, typically is rotatably connected to a free-rolling wheel, for example, via a power transmission system such as gears, chains and sprockets, or pulleys. The free-rolling wheel is typically mounted on an axle connected to the frame of the planting apparatus on which the seed dispensers are mounted. Other means of directly or indirectly driving a seed metering device directly or indirectly off of a free-rolling wheel are known in the art as well, and will not be discussed herein in detail.
The rate at which seeds are dispensed may be and often is determined by manually adjusting the drive mechanism connection (such as a gear or chain and sprocket ratio adjustment), which in turn determines the rate of revolution of the drive mechanism, and, as a result, the seed dispensing disc, per revolution of the free-rolling wheel. By manually adjusting the drive mechanism connection, the operator can determine the number of seeds to be delivered per linear distance travelled by the planting apparatus, assuming a substantially pure rolling motion (i.e., absolutely no slippage or sliding) by the free-rolling wheel of the planting apparatus.
In order to economically obtain the maximum crop yield per acre while minimizing costs from, for example, seed waste from planting more seeds than a particular portion of the field will have nutrients to support, the operator of the planting apparatus (hereinafter "farmer") must be able to accurately control and accurately adjust (preferably while the planting apparatus is in motion) the number of seeds planted per linear distance of travel by the planting apparatus.
It has been determined that different portions of a field being planted by a farmer may vary widely in ability to supply nutrients to support a crop; i.e., a farmer's field may have a wide spectrum of high yield, medium yield, and low yield areas scattered throughout the acreage to be farmed. Ideally, a farmer would like to accurately plant seeds closer together linearly in a high yield area, and farther apart linearly in a low yield area, and to be able to do so without stopping the planting apparatus and, e.g., dismantling and readjusting the drive mechanism each time the planting apparatus travels from high to medium to low yield areas of a particular field. Because of the farmer's inability with many prior art planting devices to accurately vary linear seed spacing without the time-consuming and labor intensive practice of stopping and adjusting, e.g., the drive mechanism for the seed dispensers, farmers often set the linear plant spacing at a predetermined constant rate (sometimes referred to as an "average rate") for the field. This practice resulted in (1) lower than optimum crop yield in high yield areas of the field due to underplanting, or (2) overplanting (resulting in seed waste) in low yield areas of the field, or (3) both. These outcomes had adverse economic impacts on the farmer.
In order to optimize crop yield by accurately dispensing seeds at predetermined linear spacings, a farmer would prefer to be able to accurately control the distance between seeds. For example, when planting corn, farmers may prefer the nominal linear distance between seeds in a medium yield portion of the field to be 8.0 inches, in high yield portions to be 6.0 inches, and in low yield portions to be 12.0 inches. The farmer might prefer a wide spectrum of other spacings to be available as well, depending upon, among other things, soil conditions. Consequently, a farmer would prefer to be able to accurately control nominal linear seed spacing within increments of 0.125 inches or less in such applications. The nominal spacing and increments may, of course, vary, depending upon, among other things, the crop.
Prior art automated planting apparatus in which the seed dispensing rate depended upon a drive mechanism coupled to a free-rolling wheel of the planting apparatus lacked the ability to control linear seed spacing with the accuracy desired. This is due, in part, to the fact that in ordinary farming conditions the free-rolling wheel connected to the drive mechanism of the planting apparatus does not operate with a pure rolling motion, and unless the free-rolling wheel connected to the drive mechanism purely rolls, seeds are dispensed at a rate that will not accurately and consistently achieve the desired spacing per linear distance travelled by the planting apparatus.
For example, in the crumbling topsoil typically encountered in many farming applications, the free-rolling wheel of the planting apparatus pulled by the tractor may slide intermittently and at unpredictable intervals. When the wheel slides instead of rolls, the rotating drive mechanism connected to the aforesaid wheel which operates the seed dispenser will not drive the seed dispenser (or will drive it at a slower rate than if it were purely rolling) which results in less seeds being dispensed than desired per linear distance travelled by the planting apparatus. This is because the planting apparatus may travel forward despite the non-rotation of the free-rolling wheel as a result of the sliding mode of travel. Similarly, as the free-rolling wheel encounters crumbling topsoil beneath it, the wheel may over-rotate, or slip (i.e., although the wheel rotates, the planting apparatus does not move relative to the ground, similar to an automobile spinning its wheels in the snow), resulting in the seed dispenser dispensing seeds at a rate greater than that desired per linear distance travelled by the planting apparatus.